Long-distance Spore Transport: Vertical Sections of Spore Clouds over the Sea

Abstract

To measure the rate at which spore clouds were depleted over the sea, spores were collected with isokinetic suction impactors mounted in aircraft of the Meteorological Research Flight, Farnborough. Remote from sources able to replenish spore clouds, preferential deposition from the lower layers caused 'erosion' of the base of vertical profiles of spore concentration leaving maxima at heights between 500 and 1500 m. To determine vertical spore distributions throughout the largest possible distance downwind of the English coast, a saw-tooth flight plan of alternating ascent and descent was used. Of four flights, two encountered favourable weather, rain interfered with sampling on one and unexpected winds across the track converted another into an unintended but interesting cross-wind section of spore distribution.Pollens and Cladosporium spores were counted as examples of large and small spores liberated typically by day, and a composite group of spores liberated in damp air was chosen as an indicator of spores liberated mostly at night. In two flights in fine weather maximum spore concentrations occurred hundreds of miles off-shore. Diagrams showing height, distance from the coast and lines of equal spore concentration (' isospores ') demonstrated discrete clouds of each marker spore type. Pollen and Cladosporium clouds were centred at approximately the same distances from the coast but with the pollen about 500m. lower, probably because the pollen grains sedimented faster. Maximum concentrations o€ the damp-air group sometimes coincided and sometimes alternated with the day-liberated groups. Known periodicities of these spores over land, surface air trajectories and previous weather, suggested that the spore clouds which the aircraft overtook over the North Sea, were the residue of those produced from the British Isles on previous days or nights. Interpretation of the results was limited by meteorological uncertainties, the geographical complexity of probable source areas, and perhaps most by changes in the number of spores crossing the coast at different times of day, which prevented accurate measurement of rates of spore deposition.Spores of many species were recognized over the North Sea. The plant pathogens included established distant migrants such as uredospores of Puccinia graminis, which apparently originated east of the Baltic. The viability of the spores was not tested, but it seems safe to assume that distant transport is both frequent and extensive and probably important in temperate latitudes in summer.

Contribution of fungi to primary biogenic aerosols in the atmosphere: wet and dry discharged spores, carbohydrates, and inorganic ions

“…The average value of mannitol concentrations reported for PM with particle diameters up to 10 µm or more at extratropical measurement locations (25 ng m −3 , Table A3, lines 11-17) is assumed to be representative for a well-mixed continental boundary layer (CBL) with an average height of ∼1 km (Seinfeld and Pandis, 1998;Strawbridge and Snyder, 2004;Elbert, 2006). The following evidence supports these assumptions as conservative: significantly higher mannitol concentrations reported from tropical regions (Table A3); significantly higher and well-mixed day-time CBLs in tropical regions (Graham et al, 2003b); observation of elevated spore concentrations in the upper part of the CBL (Meier and Artschwager, 1938;Hirst et al, 1967b;Linskens and Jorde, 1986).…”

“…Air masses with low concentrations of spores can be intercepted by plumes with very high concentrations (Hirst et al, 1967b;Chatterjee and Hargreave, 1974;Burch and Levetin, 2002). Table A2 summarizes ambient concentrations of AAS (a) and ABS (b) reported in earlier studies, and the results of our microscopic investigations of aerosol filter samples collected in the tropical rainforest of Amazonia.…”

“…Since then, aircraft, balloon, and rocket measurements have shown that PBA particles are not only ubiquitous over land and oceans but also transported to high altitudes (up to 80 km) and over long distances (Scheppergrell, 1924;Proctor, 1934;Meier, 1935;Rogers and Meier, 1936;Pady et al, 1950;Hirst et al, 1967b;Gregory, 1978;Imshenetsky et al, 1978;Watson and DeSousa, 1983;Griffin et al, 2001;McCarthy, 2001;Brown and Hovmoller, 2002;Yeo and Kim, 2002;Wainwright et al, 2003;Griffin, 2004;Prospero et al, 2005).…”

Aeropalynology in Britain—an Outline

“…Newman (1948) trapped pollen and fungal spores over the Tasman Sea and Polunin and his co-workers, over the North Pole (Polunin, 1951;Polunin and Kelly, 1952). More recently high concentrations of spores have been observed in summer over both the English Channel and the North Sea (Hirst, Stedman & Hurst, 1967) and in general spores are often transported far and in great numbers (Hirst, 1961a;Hirst and Hurst, 1967). Gregory (1962b) and Pearson (1962) tentatively identified fungus spores and pollen grains respectively in meteorites.…”

“…More recently volumetric counts have been obtained by means of a specially designed 'aircraft impactor' (Hirst and Hurst, 1967;Hirst, Stedman and Hogg, 1967). The demands of hospital hygiene have led to important advances in aerobiological techniques which, though they have been devised for assessing bacteria in the air, have obvious possibilities in relation to plant spores.…”